MOSCOW — Intensifying his political attacks on Russia’s opposition, the leader of Russia’s Chechnya republic posted a video Monday that appears to show Mikhail Kasyanov, a former prime minister who now heads an opposition party, in the crosshairs of a rifle’s scope.

Kasyanov said in a statement that he considered the video posted online by Chechen leader Ramzan Kadyrov as a murder threat and he planned to appeal to Russian law-enforcement agencies.

Kasyanov is chairman of the opposition People’s Freedom Party. He had shared the post with Boris Nemtsov until Nemtsov was shot dead near the Kremlin a year ago.

The suspects under arrest in Nemtsov’s slaying are all Chechens, including the suspected triggerman, a former officer in Kadyrov’s security forces. Kadyrov has denied any involvement.

The Chechen strongman ramped up his campaign against opposition leaders last month by calling for them to be prosecuted as traitors.

Human rights groups have urged Russian President Vladimir Putin to respond to Kadyrov’s veiled threats against opposition figures. Putin showed his support for Kadyrov last week by thanking him for ‘‘working effectively.’’

Associated Press